Process of making foot cushioning devices



March 13, 196 w. M. SCHOLL 3,025,206

PROCESS OF MAKING FOOT CUSHIONING DEVICES Original Filed Sept. 12, 19562 Sheets-Sheet 1 521E? MAC/AM M fay/044 March 13, 1962 w. M. SCHOLL3,025,206

PROCESS OF MAKING FOOT CUSHIONING DEVICES Original Filed Sept. 12, 19562 Sheets-Sheet 2 EIE. 5

E-Zazzfm Mum/v M Scwozp 3,025,206 PROCESS OF MAKING FOOT CUfifliflNfiJGDEVICES William M. Scholl, 211-213 W. Schiller St, Chicago, lil.Original application Sept. 12, 1956, Ser. No. 609,453,

now Patent No. 2,917,842, dated Dec. 22, 1956. Divided and thisapplication Apr. 3, H58, Ser. No.

1 Claim. Cl. 156-219) This invention relates to improvements in aprocess of making foot cushioning devices, the invention being highlydesirable for the production of various types of foot cushioning devicesor appliances including heel seats, full or partial insoles, with orwithout lifts at judicious or desired locations, callous or buniontreating pads and the like, and various other types of devices foralleviating afflictions of the foot, the devices not being necessarilylimited to appliances of the character inserted in articles of footwearrather than attached directly to the foot of the user.

The instant application is a division of my copending applicationentitled Foot Cushioning Devices, filed September 12, 1956, Serial No.609,453, now Patent No. 2,917,842, which copending application isdirected to and claims the devices produced by the process of theinstant application.

In the past, cushioning and corrective appliances for the feet have beenproduced by many and various processes and methods. In some instances,laminations of insoles or the like were joined together by heat sealing,but in no instance of which I am aware has cushioning material ever beenheat sealed to anything else, the heat sealed devices heretofore madefor corrective aid to the foot not embodying any cushioning meanswhatever. Even with such devices, the process of heat sealing wasaccomplished either in an objectionably expensive manner, and mostfrequently the heat sealing operation resulted in the provision of anoversize or awkward seam which rendered the appliances unsightly,cumbersome, and frequently ill fitting. It is well known that in aproperly constructed shoe, the built-in insole acquires an upwardcurvature around the margin thereof in the construction of the shoe, andwhen it is desired to have the cushioning device present a flat surfacebeneath the foot of the user, some special shaping has to be made tocompensate for the shape of the built-in insole, and that could not beaccomplished with heat sealed devices made by processes heretoforeknown.

With the foregoing in mind, it is an important object of the instantinvention to provide a process of making foot cushioning and correctivedevices, the process embodying the step of heat sealing parts of thedevice together in such a manner that the resultant heat seal seam is arelatively fine line, and the method can be practiced so as to provide aheat seal seam that is substantially invisible when the device is inposition for use.

It is also an object of this invention to provide a process for makingfoot corrective and cushioning devices, the process of embodying a stepof heat sealing parts of each device together in a manner to give theresultant product a shape enabling it to compensate for the upwardlycurved side edges of the structural insole of the shoe, and present arelatively flat surface to the foot of the user, in the event the deviceis in the form of an insole or other appliance for disposition beneaththe plantar surface of the foot.

Also an object of the instant invention is the provision of a processfor making foot cushioning or corrective devices, the process embodyingthe step of heat sealing cushioning material to some other material inthe making of the device.

hired htates Patent ice Still another object of the instant invention isthe provision of a process of making foot cushioning or correctivedevices, in which process a plurality of sheets of cushioning materialmay be connected by heat sealing to a cover sheet or the like.

The invention also contemplates the provision of a process of makingfoot cushioning and corrective appliances, in which process a thicklayer of cushioning material is heat sealed to a thin cover layer by afine line heat seal seam defining the outer edge of the resultantarticle.

Another desiderattun of the instant invention is the provision of aprocess for making foot cushioning and corrective devices, in whichprocess a relatively thick layer of cushioning material is heat sealedto a thin cover layer in such a manner that the cushioning layer isprovided with an arcuate margin adjacent the heat seal seam; or, inother words, the cushion layer curves or gradually diminishes inthickness toward a rather fine line heat seal seam.

The process of the instant invention also embodies the novel step ofproviding foot cushioning or corrective appliances from stock sheets ofindefinite size by heat sealing the sheets together in an intermediatelocation, and in the same operation providing a readily disruptibleseverance line at the heat seal seam, so that the waste material mayreadily be separated from the completed article.

The process also contemplates the step of utilizing sheets of materialof different'sizes, and heat sealing these sheets together, whereby anadded lift of cushioning or other material may be disposed at ajudicious location in the device.

The practice of the instant method is extremely economical and resultsin the provision of devices or appliances that possess substantially allthe advantages de sired therein, and many more advantages than werepossible to incorporate in such appliances by methods heretofore known.The practice of the instant method therefore results in the provision ofa better product than could heretofore be made. Among the advantagespossessed by the cushioning part of the device are its light weight,softness, the fact that it conforms and molds to high points of the footbut does not mat or flatten, it gives a continuous properly balancedcushioning effect to parts of the foot at all times with uniformcompression and balanced weight bearing, it possesses excellentresiliency, does not press back against the foot although it absorbs theshock from foot contact therewith to a better extent than materialsheretofore used, and it is further pervious to air and so possessesventilative properties. Since the cushioning material preferably hasintel-communicating cells, it' not only provides adequate ventilationbut also may be medicated with powder or the like.

Among the advantages possessed by the resultant device as a whole may beincluded washability without shrinkage, quick drying, excellent wearingqualities, and durability, it is non-inflammable, is non-hygroscopic,nonskid, has more than necessary strength, does not discolor, may beprovided in various attractive colors, possesses excellent eye appeal,does not age or deteriorate over a considerable period of time, is notaffected by perspiration, cleaning fluids, foot acids and the like, hasinsulating properties, has no inherent odor, is hygienic, and resistsfungus and bacteria. The materials that may be used by the practice ofthe instant invention are also resistant to rot, mildew, oils andgreases, alkalis, and most common reagents.

While some of the more salient features, characteristics and advantagesof the instant invention have been above pointed out, others will becomeapparent from the following disclosures, taken in conjunction with theaccompanying drawings in which FIGURE 1 is a bottom plan view of anelectrode die that may be used in practicing the method of the instantinvention;

FIGURE 2 is a fragmentary bottom plan view illustrating a pair of fullsize insoles made in accordance with the instant invention, with the useof the die of FIGURE 1, and an allochiral die, showing the same prior toremoval from the stock material;

FIGURE 3 is an enlarged fragmentary transverse cross-sectional viewillustrating the use of the die of FIGURE 1 in the making of an insoleseen in FIGURE 2;

FIGURE 4 is a transverse vertical sectional view through a finishedinsole itself;

FIGURE 5 is a plan view of a foot cushioning appliance of differentconstruction made also by the practice of the instant invention;

FIGURE 6 is a greatly enlarged fragmentary vertical sectional view takensubstantially as indicated by the lines VIVI of FIGURE 5, looking in thedirection of the arrows;

FIGURE 7 is a greatly enlarged vertical sectional view takensubstantially as indicated by the lines VIIVH of FIGURE 5; and

FIGURE 8 is a fragmentary plan view of a cover sheet that may beincorporated with a product resulting from the practice of the instantinvention.

As shown on the drawings:

In the practice of the instant invention, insofar as the heat sealingoperation is concerned, a known type of electronic heat sealingapparatus is utilized, wherein the material to be heat sealed is placedbetween a pair of electrodes or dies. One of these electrodes may beshaped to define the desired outline of the resultant article, while theother may be similarly shaped if deemed necessary, or be in the form ofa flat plate. The dies or electrodes are usually mounted in a suitablepress capable of providing'the necessary pressure. The electrodes send ahigh frequency current through the material being heat sealed to heatthat material above its melting point, and the pressure between the diesfuses the material in the heated regions. The entire heat sealingoperation, of course, requires only an extremely short period of time,measured in seconds or fractions thereof.

In the making of a foot corrective or cushioning appliance by way of theinstant invention, at least two sheets of materials are used, one beinga cover sheet and the other preferably a cushioning sheet. Thecushioning sheet is preferably a thermoplastic foam, having the generalappearance of foam latex, but a material that not only can be heatsealed but is more shock absorbing than foam latex. While a number ofthermoplastic foam materials may be suitable for the purpose, by way ofspecific example and not by way of limitation, I may mention that a verysatisfactory substance is vinyl foam made from a liquid compositiongenerically known as a plastisol. The plastisol is expanded preferablyby the use of an inert gas, and then cured in the expanded condition toprovide a lightweight structural material which is highly flexible,resilient, and possesses intercommunicating cells. The plastisol maysatisfactorily be a dispersion or suspension of polyvinyl chlorideresin, or a copolymer in one or more plasticizers selected from a largenumber of high boiling esters, for example, such as dioctyl phthalate,dioctyl adipate, dicapryl phthalate, etc.

The cushioning sheet is preferably considerably thicker than the coversheet. The cover sheet may be of material having the same chemicalconstituency as the cushioning sheet, but is made under a differentprocess to provide a relatively thin sheet or unsupported film. In thisinstance, the resins and plasticizers may be charged directly into aBanbury mill, and from there pass to a calender which rolls out thefinished product. No expansion process is relied upon, so that thecovering material will have a density of about lbs. per cubic foot asopposed to the 5 to 7 lbs. per cubic foot for the cushioning material.The covering material may be in any desired color, and may be givensubstantially any desired external appearance, such as artificialleather, a multi-color, a plain color, a mottled appearance, etc.

In FIGURE 1 I have illustrated one form of die which may be used in thepractice of the instant method. The die shown in the drawings is of ashape to provide a full cushion insole for insertion in a shoe or thelike. Obviously, the die would have the shape desired in the resultantdevice. The die is somewhat diagrammatically illustrated in FIGURES 1and 3, and comprises a backing plate 1 which may be of steel orequivalent material, and a depending die element, generally indicated bynumeral 2, which is preferably of brass or equivalently electricallyconductive material. The die member 2 is preferably made rather wide asseen particularly in FIGURE 3, and is shaped to provide substantially aknife edge 3 with an upwardly and inwardly sloping surface 4 leadingaway from that knife edge. In the illustrated instance, there is asharper slope outwardly of the knife edge 3, as indicated at 5, but theparticular shape on the outer side of the knife edge is of no greatimportance in comparison with the shape of the sloping surface 4 insidethe knife edge. The illustrated die is for the making of an insole tounderlie the left foot of the user, and it will be understood that anallochiral die will be utilized to provide an insole for the right foot.In the practice of the instant invention, obviously as many dies as maybe desired may be utilized in a press at one time.

In the making of the cushion insole selected as one example of a productthat may be made by the instant method, it is presumed that the presshas a flat platelike lower die. Numeral 6 may indicate either the lowerdie itself or a buffer of insulating material such as a phenoliccondensation product placed upon the electrode plate, if a buffer isdeemed necessary. On the top of the plate 6, a sheet 7 of cover materialof the character above described is placed, and superposed on that thincover sheet is a much thicker sheet 8 of cushioning material which, asexplained above, is thermoplastic foam. It is not essential that thesheet 8 be on top the sheet 7, as illustrated.

The sheets may be of the same area, but are preferably sufiicientlylarge for the forming of a number of appliances therefrom, foreconomical reasons.

In FIGURE 3, the upper die 2 is illustrated just prior to the completionof a heat sealing operation. The developed heat in the thermoplasticsheets will of course be concentrated beneath the knife edge 3 of thedie, which defines the ultimate heat seal seam, but some of the heatingeffect will be dissipated along the inclined face 4 of the die, so thatthere will be a gradually reducing effect of the heat seal upon themarginal portion of the foam layer 8 inside the knife edge 3.

When the die is pressed downwardly, the layers or sheets 7 and 8 will befused together immediately under the knife edge 3 in a heat seal seam,which is preferably not noticeably thicker than the thin sheet 7 alone.The thick cushioning layer 8 is compressed during this operation, and afine line heat seal seam 9 results, defining and outlining a completedcushion insole 10. This heat seal seam 9 also provides a readilydisruptable line whereby the finished insole may readily and easily beremoved from the scrap material or remainder of the stock sheets 7 and8. The removal of the finished article from the balance of the stocksheets at the heat seal seam does not result in injuring the connectionof the two layers forming the resultant article in any manner.

Now with reference more particularly to FIGURE 4, it will be noted thatthe gradual reduction of the effect of the heat sealing operation byvirtue of the inclined face 4 of the die results in providing a roundedor curvate margin 11 in the cushion layer 8. In other words, the cushionlayer has a marginal portion inside the heat seal seam 9 which graduallydecreases in thickness toward the fine line heat seal seam. This resultis obtained notwithstanding the fact that both layers of material werepreferably initially flat. The rounded margin 11 is important in that itpermits the resultant insole to lie in the shoe and present a flat uppersurface to the foot of the user, the curvate marginal portioneffectively compensating for the up ward inclination of the margin ofthe structural insole in a shoe. Further, this curvate marginal portionrenders the actual junction between the cover layer 7 and the cushioninglayer 8 substantially unnoticeable, and the heat seal seam itself issmooth and clean and does not cause any unintentional distortion of thedevice when placed in a shoe or the like.

Preferably, the heat sealing operation unites the two layers only at thebounding edges thereof and these layers are not secured to each otherinside the heat seal seam 9. This is indicated by the exaggeratedshowing of a space 12 in FIGURE 4 between the cover 7 and the cushionlayer 8. This arrangement prevents wrinkling of the insole when placedin a shoe, and further prevents an inward pull on the edges of theinsole due to pressure on the same by the metatarsal heads orexcrescences on the plantar surface of a foot. 1

The practice of the instant invention is extremely simple andeconomical. It is simply necessary to place the sheets 7 and 8 inposition, and bring down the upper die. The heat seal seam and compositetear line are provided almost instantaneously and the layers of theresultant device are joined together positively and durably by the heatseal seam, with the curvate marginal portion on the cushion layer. Inshort, the complete practice of the instant invention amounts to littlemore than a stamping operation insofar as time and labor are concerned.

The instant invention may equally as well be practiced with more thantwo layers or laminations of material. It makes no difference whetherthe added laminations are like the thin cover layer or like thecushioning layer. Thus, a lift or the like may be added wherever desiredin a foot cushioning or corrective device. By way of example andillustration, in FIGURES 5, 6 and 7 I have shown an insole of afore-shortened type having a projecting portion to underlie at least thebase of the great toe while the other toes may project entirely off theinsole. This form of device is preferably made of the same materials asabove described, the layers being heat sealed together in the samemanner as above described, although it will be understood the upper diewill have a shape in keeping with the shape of this particular article.

The form of device shown in FIGURES 5, 6 and 7 comprises a thin coverlayer 13, and a relatively thick cushion layer or sheet 14 heat sealedtogether in the manner above described at the bounding edges, as indi-.

cated at 15. The sheets 13 and 14 are of substantially equal area, butare shaped to provide a projection 16 to underlie at least the rearportion of the great toe of the foot. In some instances, it is desirableor necessary to give an added lift to the great toe. To this end, anextra layer of cushioning material 17 may be disposed between the layers13 and 14, as seen clearly in FIGURES and 6, this layer 17 being ofsuflicient size to extend within the projection 16 of the foreshortenedinsole. The lift 17 is of the same character as the cushioning layer 14and may be freely disposed between the layers 13 and 14 when the heatsealing operation is performed. The lift 17 is preferably retained inposition by having its edge caught in the heat seal seam 15, while theinside edge 18 of the lift 17 remains free and unsecured to either ofthe other sheets. The added thickness of material, such as the lift 17,provides no problem whatever in performing the heat sealing operation,although it might be necessary to increase the die pressure to someextent. The resultant heat seal seam is the same as above described, anda fine line seam is provided nothwithstanding the additional layer ofmaterial.

It will be apparent that a lift such as the insert 17 may be provided atany desired or judicious location in a cushioning or correctiveappliance made by practicing the instant invention.

In FIGURE 8, I have illustrated a fragmentary section of a cover sheet19 provided with numerous perforations therein to provide additionalventilation in the finished article; as well as to indicate thatregardless of whether or not the cover sheet is perforated, the heatsealing operation is the same. A smooth, even and fine heat seal seamwill result due to the fusing of the layers together, and there will beno rough edges, even though the seam passes directly through one or moreperforations. Heretofore, when a perforated cover was used and a devicestamped out of stock sheets, rough edges were left where perforationswere cut, but that cannot happen in the practice of the instant method.

It will be understood that modifications and variations may be effectedWithout departing fro-m the scope of the novel concepts of the presentinvention.

I claim as my invention:

The method of making a cushioning appliance, including the step ofsuperposing a thin cover sheet of flexible thermoplastic film, and asubstantially thicker sheet of flexible thermoplastic synthetic resinfoam, and with a die having a fine line heat sealing working edgecomprising an outline of the appliance heat sealing and fusing thesheets together only where contacted by and immediately adjacent to saidfine line working edge and thereby simultaneously forming a seamdefining the outline of the appliance and providing a readilydisruptable fine edge tear line immediately adjacent the heat seal scam,in the heat sealing of the seam gradually reducing the effect of theheat seal inwardly of the seam to provide a rounded margin on the foamsheet gradually reducing the thickness to a fine edge junction with thecover sheet substantially coinciding with said tear line, and thenseparating the appliance from the remainder of said sheets by tearingthe appliance free along said tear line.

References Cited in the file of this patent UNITED STATES PATENTS2,425,388 Oestricher Aug. 12, 1947 2,631,646 Gannon et al Mar. 17, 19532,658,288 Scholl Nov. 10, 1953 2,677,906 Reed May 11, 1954 2,702,769Alderfer Feb. 22, 1955 2,806,812 Merz Sept. 17, 1957 2,815,306 WassermanDec. 3, 1957 2,878,153 Hacklander -Mar. 17, 1959 OTHER REFERENCES ModernPlastics, vol. 32, November 1954, pages 215-216.

